Use of CpG oligodeoxynucleotides to induce angiogenesis

ABSTRACT

This disclosure provides a method of inducing production of vascular endothelial growth factor by a cell. The method includes contacting the cell with a CpG oligonucleotide, thereby inducing the production of vascular endothelial growth factor by the cell. The disclosure further provides a method inducing neovascularization in a tissue. This method includes comprising introducing a CpG oligodeoxynucleotide into an area of the tissue wherein the formation of new blood vessels is desired, thereby inducing neovascularization in the area of the tissue.

This is the § 371 U.S. National Stage of International Application No. PCT/US02/40955, filed Dec. 19, 2002, which was published in English under PCT Article 21(2), which in turn claims the benefit of U.S. Provisional Application No. 60/343,457, filed Dec. 20, 2001, which is incorporated by reference herein in its entirety.

FIELD

This application relates to the field of angiogenesis, more specifically to the use of CpG oligodeoxynucleotides to promote angiogenesis.

BACKGROUND

Angiogenesis, the process of developing a hemovascular network, is essential for the growth of solid tumors and is a component of normal wound healing and growth processes. It has also been implicated in the pathophysiology of atherogenesis, arthritis, comeal neovascularization, and diabetic retinopathy. It is characterized by the directed growth of new capillaries toward a specific stimulus. This growth, mediated by the migration of endothelial cells, may proceed independently of endothelial cell mitosis.

The molecular messengers responsible for the process of angiogenesis have long been sought. For example, Greenblatt et al., J. Natl. Cancer Inst. 41:111-124, 1968, concluded that tumor-induced neovascularization is mediated by a diffusible substance. Subsequently, a variety of soluble mediators have been implicated in the induction of neovascularization. These include prostaglandins (Auerbach, in Lymphokines, Pick and Landy, eds., 69-88, Academic Press, New York, 1981), human urokinase (Berman et al., Invest. Opthalm. Vis. Sci. 22:191-199, 1982), copper (Raju et al., J. Natl. Cancer Inst. 69:1183-1188, 1982), and various “angiogenesis factors” (e.g., see U.S. Pat. No. 4,916,073).

Angiogenesis factors play an important role in wound healing (Rettura et al., FASEB Abstract #4309, 61st Annual Meeting, Chicago, 1977) and likely play a role in the development of malignancies (Klagsburn et al., Cancer Res. 36:110-114, 1976; and Brem et al., Science 195:880-881, 1977), hence it would clearly be advantageous to identify new angiogenic agents.

DNA is a complex macromolecule whose activities are influenced by its base composition and base modification, as well as helical orientation. Bacterial DNA, as well as certain synthetic oligodeoxynucleotides (ODNs) containing umnethylated CpG sequences can induce proliferation and immunoglobulin production by murine B cells. Unmethylated CpG dinucleotides are more frequent in the genomes of bacteria and viruses than vertebrates. Recent studies suggest that immune recognition of these motifs may contribute to the host's innate immune response. (Klinman et al, Proc. Natl. Acad. Sci. USA 93:2879, 1996;. Yi et al, J. Immun. 157:5394, 1996; Liang et al, J. Clin. Invest. II 9:89, 1996; Krieg et al., Nature 374:546, 1995).

In mice, CpG DNA induces proliferation in almost all (>95%) of B cells and increases immunoglobulin secretion. This B-cell activation by CpG DNA is T-cell independent and antigen non-specific. In addition to its direct effects on B cells, CpG DNA also directly activates monocytes, macrophages, and dendritic cells to secrete a variety of cytokines. These cytokines stimulate natural killer (NK) cells to secrete γ-interferon (IFN-γ) and have increased lytic activity. However, although some of the effects of oligodeoxynucleotides containing unmethylated CpGs are known, many effects have yet to be elucidated.

SUMMARY

Methods of increasing angiogenesis are disclosed herein. The methods include administering an effective amount of a CpG oligodeoxynucleotide to increase angiogenesis.

For example, this disclosure provides a method of inducing production of vascular endothelial growth factor by a cell. The method includes contacting the cell with a CpG oligonulcleotide, thereby inducing the production of vascular endothelial growth factor by the cell.

The disclosure further provides a method of inducing neovascularization in a tissue. This method includes introducing a CpG oligodeoxynucleotide into an area of the tissue wherein the formation of new blood vessels is desired, thereby inducing neovascularization in the area of the tissue.

A method for screening for agents that inhibit neovascularization is also disclosed herein. The method includes administering a CpG oligodeoxynucleotide to a non-human mammal, and administering the agent to the non-human mammal. Inihibition of angiogenesis in the non-human mammal indicates that the agent may be effective in inhibiting neovascularization.

The foregoing and other features and advantages will become more apparent from the following detailed description of several embodiments, which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a set of digital images demonstrating that HSV-DNA and CpG ODN induces angiogenesis. Representative 40×images are shown from day 4 post implantation. FIGS. 1A-F are digital images documenting angiogenesis induced by VEGF (FIG. 1A), vehicle alone (FIG. 1B), HSV DNA (FIG. 1C), herring sperm DNA (FIG. 1D), CpG ODN (FIG. 1E) and control ODN (FIG. 1E). Pellets containing 0.5-5 μg of HSV DNA or VEGF were implanted into corneal micropockets. The degree of neovascularization was compared to 5 μg of herring sperm DNA (4 mice/group). The mean angiogenic area from all samples is shown in FIG. 1G.

FIG. 2 shows the dose and kinetics of the angiogenic response to CpG DNA. FIG. 2A shows a dose-response of new blood vessel formation was monitored using the comeal micropocket assay 4 days post implantation. FIG. 2B shows the kinetics of neovascularization were measured 1-5 days post implantation. All results represent the mean of 4 animals/group.

FIG. 3 is a set of digital images showing that CpG DNA induces inflammation and VEGF expression in corneal micropockets. Pellets containing 1 μg of CpG or control ODN were implanted into mouse corneas. Frozen sections from these eyes were stained for VEGF expressing cells 4 days later. FIGS. 3A and 3B are digital images showing that positive cells are present in the ipsilateral site of the pellet implanted cornea. FIG. 3C is a bar graph of the number of infiltrating cells in the comeal stroma. Each number represented the mean total cellular infiltrates derived from 4 central corneal sections from two eyes. Magnification is 200×.

FIG. 4 is a bar graph showing HSV DNA and CpG ODN induced angiogenic responses react to anti-mVEGF antibody administration. The results demonstrated that anti-mVEGF antibody suppresses CpG DNA induced angiogenesis. Pellets containing 45 ng of rmVEGF164, 1 ug of ODN, or 2 ug of HSV or herring sperm DNA were placed in corneal pockets. Anti-mVEGF antibody (5 μg in 5 μl of PBS) was injected subconjunctivally into the eyes just prior to and 2 days after pellet implantation. The eyes were observed using stereomicroscopy, and neovascularization was measured in 4 mice/group. The solid black bar represents+anti-mVEGF Ab.

FIG. 5 is a digital image of a PCR analysis that demonstrates that CpG ODN upregulates VEGF mRNA expression in J774A.1 cells. J774A.1 cells were incubated for 3-6 hours with 3 μg/ml of HSV-DNA, herring sperm DNA, CpG or control ODN. Total RNA was extracted from 10⁶ cells, reverse transcribed and PCR amplified to detect the 120, 164, 188 isoforms of VEGF. β-actin served as the positive control and standard for semi-quantitative RT-PCR.

FIG. 6 is a set of digital images documenting that CpG ODN induces VEGF production. J774A.1 cells were incubated in two-well chamber slides with 2 μg/ml of FITC-CpG (FIGS. 6A and 6B) or control (FIG. 6C) ODN for 18 hours. The cells were fixed and stained for mVEGF at 18 hours (FIGS. 6B and 6C). Note that all cells expressing VEGF stained with FITC-CpG ODN. * An amplified photo image showed FITC-CpG ODN filled in the cytoplasm of a J774A.1 cell at 18 hours post stimulation. Magnification is 400.

SEQUENCE LISTING

The nucleic and amino acid sequences listed in the accompanying sequence listing are shown using standard letter abbreviations for nucleotide bases, and three letter code for amino acids, as defined in 37 C.F.R. 1.822. In the accompanying sequence listing:

SEQ ID NOs: 1-4 are the nucleic acid sequences of K type CpG ODNs.

SEQ ID NO: 5 and SEQ ID NO: 6 are the nucleic acid sequence of D type CpG ODNs.

SEQ ID NO: 7 and SEQ ID NO: 8 are the nucleic acid sequences of exemplary angiogenic CpG ODNs.

SEQ ID NO: 9 is the nucleic acid sequence of an exemplary control (non-angiogenic) ODN.

SEQ ID NO: 10 and SEQ ID NO: 11 are the nucleic acid sequences of examples of primers that can be used to amplify VEGF nucleic acid.

SEQ ID NOs: 12-51 are the nucleic acid sequences of exemplary D ODN sequences and D ODN control sequences.

SEQ ID NOs: 52-106 are the nucleic acid sequences of exemplary K ODN sequences and K ODN control sequences.

DETAILED DESCRIPTION

I. Abbreviations

Ab: antibody

CpG ODN: an oligodeoxynucleotide (either a D or a K type) including a CpG motif, as defined herein.

HSV: Herpes Simplex Virus.

mm: millimeter

mRNA: messenger ribonucleic acid.

ODN: oligodeoxynucleotide

VEGF: vascular endothelial growth factor. Recombinant murine VEGF is indicated by “mVEGF” or rmVEGF.” Recombinant human VEGF is indicated by “hVEGF” or “rhVEGF.”

μg: microgram

II. Terms

Unless otherwise noted, technical terms are used according to conventional usage. Definitions of common terms in molecular biology may be found in Benjamin Lewin, Genes V, published by Oxford University Press, 1994 (ISBN 0-19-854287-9); Kendrew et al. (eds.), The Encyclopedia of Molecular Biology, published by Blackwell Science Ltd., 1994 (ISBN 0-632-02182-9); and Robert A. Meyers (ed.), Molecular Biology and Biotechnology: a Comprehensive Desk Reference, published by VCH Publishers, Inc., 1995 (ISBN 1-56081-569-8).

Unless otherwise explained, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The singular terms “a,” “an,” and “the” include plural referents unless context clearly indicates otherwise. Similarly, the word “or” is intended to include “and” unless the context clearly indicates otherwise. It is further to be understood that all base sizes or amino acid sizes, and all molecular weight or molecular mass values, given for nucleic acids or polypeptides are approximate, and are provided for description. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. In case of conflict, the present specification, including explanations of terms, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

In order to facilitate review of the various embodiments of the invention, the following explanations of specific terms are provided:

Amplification: Of a nucleic acid molecule (e.g., a DNA or RNA molecule) refers to use of a technique that increases the number of copies of a nucleic acid molecule in a specimen. An example of amplification is the polymerase chain reaction, in which a biological sample collected from a subject is contacted with a pair of oligodeoxynucleotide primers, under conditions that allow for the hybridization of the primers to nucleic acid template in the sample. The primers are extended under suitable conditions, dissociated from the template, and then re-annealed, extended, and dissociated to amplify the number of copies of the nucleic acid. The product of amplification may be characterized by electrophoresis, restriction endonuclease cleavage patterns, oligodeoxynucleotide hybridization or ligation, and/or nucleic acid sequencing using standard techniques. Other examples of amplification include strand displacement amplification, as disclosed in U.S. Pat. No. 5,744,311; transcription-free isothermal amplification, as disclosed in U.S. Pat. No. 6,033,881; repair chain reaction amplification, as disclosed in WO 90/01069; ligase chain reaction amplification, as disclosed in EP-A-320 308; gap filling ligase chain reaction amplification, as disclosed in U.S. Pat. No. 5,427,930; and NASBA™ RNA transcription-free amplification, as disclosed in U.S. Pat. No. 6,025,134. Amplification reactions can be used to produce CpG ODN, or can be used in the detection of MRNA, such as MRNA encoding a particular angiogenic faction (e.g. VEGF).

Animal: Living multi-cellular vertebrate organisms, a category that includes, for example, mammals and birds. The term mammal includes both human and non-human mammals. Similarly, the term “subject” includes both human and veterinary subjects.

Angiogenesis: Process leading to the generation of new blood vessels through sprouting from already existing blood vessels. The process involves the migration and proliferation of endothelial cells from preexisting vessels. Angiogenesis occurs both during pre-natal development, post-natal development, and in the adult. In the adult, angiogenesis occurs during the normal cycle of the female reproductive system, wound healing, and during pathological processes such as cancer (for review see Battegay, J. Molec. Med. 73(7):333-346, 1995; Beck and D'Amore, FASEB J. 11(5):365, 1997). “Neovascularization” is development of new blood vessels in a tissue.

Angiogenic Factor: A molecule that promotes angiogenesis. A plethora of experiments have suggested that tissues secrete factors which promote angiogenesis under conditions of poor blood supply during normal and pathological angiogenesis processes. Angiogenic molecules are generated by tumor, inflammatory, and connective tissue cells in response to hypoxia and other as yet ill-defined stimuli. The first indication of the existence of such diffusible substances was gleaned from filtration experiments demonstrating that tumor cells separated from underlying tissues by filters that do not allow passage of cells are nevertheless capable of supporting vessel growth in these tissues. The formation of blood vessels is initiated and maintained by a variety of factors secreted either by the tumor cells themselves or by accessory cells. Many different growth factors and cytokines have been shown to exert chemotactic, mitogenic, modulatory or inhibitory activities on endothelial cells, smooth muscle cell and fibroblasts and can, therefore, be expected to participate in an angiogenic process in one way or another. For example, factors modulating growth, chemotactic behavior and/or functional activities of vascular endothelial cells include aFGF, bFGF, angiogenein, angiotropin, epithelial growth factor, IL-8, and vascular endothelial growth factor (VEGF), amongst others.

As many angiogenic factors are mitogenic and chemotactic for endothelial cells their biological activities can be determined in vitro by measuring the induced migration of endothelial cells or the effect of these factor on endothelial cell proliferation. Alternatively, a bioassay may be utilized for direct determination of angiogenic activities and permit repeated, long-term quantitation of angiogenesis as well as physiological characterization of angiogenic vessels. Many such assays are known in the art.

One assay employs the use of a non-vascularized mouse eye (e.g. Kenyon et al., Invest Opthalmol. Vis. Sci. 37:625, 1996; also see Examples section) or the rabbit eye (e.g., see Gaudric et al. Ophthal. Res. 24:181, 1992)., and is termed a cornea pocket assay. This assay has the advantage that new blood vessels are easily detected and essentially must be newly formed blood vessels in the normally avascular cornea. Another assay involves the use of chicken chorioallantoic membrane (the CAM assay; see Wilting et al., Anat. Embryol. 183:259, 1991). Other assays in the rat, such as the rat aortic ring model, provide reproducible assays that are often utilized to identify angiogenic agonists and antagonists (e.g. see Lichtenberg et al., Pharmacol Toxicol. 84:34, 1999).

CpG or CpG motif: A nucleic acid having a cytosine followed by a guanine linked by a phosphate bond in which the pyrimidine ring of the cytosine is unmethylated. The term “methylated CpG” refers to the methylation of the cytosine on the pyrimidine ring, usually occurring the 5-position of the pyrimidine ring. A CpG oligodeoxynucleotide is an oligodeoxynucleotide that is at least about ten nucleotides in length and includes an unmethylated CpG. CpG oligodeoxynucleotides include both D and K type oligodeoxynucleotides (see below). CpG oligodeoxynucleotides are single-stranded. The entire CpG oligodeoxynucleotide can be unmethylated or portions may be unmethylated. In one embodiment, at least the C of the 5′ CG 3′ is unmethylated.

D Type Oligodeoxynucleotide (D ODN): An oligodeoxynucleotide including an unmethylated CpG motif that has a sequence represented by the formula: 5′ RY-CpG-RY 3′ wherein the central CpG motif is unmethylated, R is A or G (a purine), and Y is C or T (a pyrimidine). D-type oligodeoxynucleotides include an unmethylated CpG dinucleotide. Inversion, replacement or methylation of the CpG reduces or abrogates the activity of the D oligodeoxynucleotide.

In one embodiment, a D type ODN is at least about 16 nucleotides in length and includes a sequence represented by the following formula: 5′-N₁N₂N₃ R₁ Y₂ CpG R₃ Y₄ N₄N₅N₆(N)_(x)(G)_(z)-3′(SEQ ID NO: 6) wherein the central CpG motif is unmethylated, R is a purine nucleotide, Y is a pyrimidine nucleotide, N is any nucleotide, X is any integer from 0 to 10, and Z is any integer from 4 to 10. Additional detailed description of D ODN sequences and their activities can be found in Verthelyi et al., J. Immunol. 166:2372-2377, 2001, which is herein incorporated by reference. Generally D ODNs can stimulate a cellular response.

Herpes Virus: There are eight known herpesviruses which are divided into three classes, denoted alpha, beta, and gamma. The herpesviruses include human herpesviruses 1, human herpes virus 2, varicella zoster virus, human cytomegalovirus, Epstein BarR virus, mouse cytomegalovirus, and human herpesvirus 8, amongst others. The structure of the herpesvirus particle is very complex. The core consists of a toroidal shape with the large DNA genome wound around a proteinaceous core. The complex capsid surrounds the core. Outside the capsid is the tegument, a protein-filled region which appears amorphous in electron micrographs. On the outside of the particle is the envelope, which contains numerous glycoproteins.

All herpesvirus genomes have a unique long (UL) and a unique short (US) region, bounded by inverted repeats. The repeats allow rearrangements of the unique regions and herpesvirus genomes exist as a mixture of 4 isomers. Herpesvirus genomes also contain multiple repeated sequences and depending on the number of these, genome size of various isolates of a particular virus can vary by up to 10 kbp.

The prototype member of the family is Herpes Simplex Virus (HSV) which is about 160 kbp in length. The complete sequence of HSV is known. There are two antigenic types, HSV-1 and HSV-2, which share antigenic cross-reactivity but different neutralization patterns and tend to produce different clinical symptoms. Man is believed to be the natural host for HSV, but the virus is also capable of infecting various animals, including rodents.

Isolated: An “isolated” nucleic acid has been substantially separated or purified away from other nucleic acid sequences in the cell of the organism in which the nucleic acid naturally occurs, i.e., other chromosomal and extrachromosomal DNA and RNA. The term “isolated” thus encompasses nucleic acids purified by standard nucleic acid purification methods. The term also embraces nucleic acids prepared by recombinant expression in a host cell as well as chemically synthesized nucleic acids.

K Type Oligodeoxynucleotide (K ODN): An oligodeoxynucleotide including an unmethylated CpG motif that has a sequence represented by the formula:

5′ N₁N₂N₃D-CpG-WN₄N₅N₆ 3′ (SEQ ID NO: 1)

wherein the central CpG motif is unmethylated, D is T, G or A, W is A or T, and N₁, N₂, N₃, N₄, N₅, and N₆ are any nucleotides. In one embodiment, D is a T. Additional detailed description of K ODN sequences and their activities can be found in the description below. Generally K ODNs can stimulate a humoral response. For example, K ODNs stimulate the production of imnmunoglobulins, such as IgM and IgG. K ODNs can also stimulate proliferation of peripheral blood mononuclear cells and increase expression of IL-6 and/or IL-12, amongst other activities.

Mammal: This term includes both human and non-human mammals.

Similarly, the term “subject” includes both human and veterinary subjects.

Nucleic acid: A deoxyribonucleotide or ribonucleotide polymer in either single or double stranded form, and unless otherwise limited, encompasses known analogues of natural nucleotides that hybridize to nucleic acids in a manner similar to naturally occurring nucleotides.

Oligonucleotide: A linear polynucleotide sequence of up to about 200 nucleotide bases in length, for example a polynucleotide (such as DNA, oligodeoxynucleotides or RNA, oligoribonucleotides) which is at least six nucleotides, for example at least 10, 15, 50, 100 or even 200 nucleotides long.

A “stabilized oligonucleotide” is an oligonucleotide that is relatively resistant to in vivo degradation (for example via an exo- or endo-nuclease). In one embodiment, a stabilized oligonucleotide has a modified phosphate backbone. One specific, non-limiting example of a stabilized oligonucleotide has a phophorothioate modified phosphate backbone (wherein at least one of the phosphate oxygens is replaced by sulfur). Other stabilized oligonucleotides include: nonionic DNA analogs, such as alkyl- and aryl-phophonates (in which the charged phosphonate oxygen is replaced by an alkyl or aryl group), phophodiester and alkylphosphotriesters, in which the charged oxygen moiety is alkylated. Oligonucleotides which contain a diol, such as tetraethyleneglycol or hexaethyleneglycol, at either or both termini have also been shown to be substantially resistant to nuclease degradation.

An “immunostimulatory oligonucleotide,” “immunostimulatory CpG containing oligodeoxynucleotide,” “CpG ODN,” refers to an oligodeoxynucleotide, which contains a cytosine, guanine dinucleotide sequence. In one embodiment, CpG ODN stimulates (e.g. has a mitogenic effect or induces cytokine production) vertebrate immune cells. CpG ODN can also stimulate angiogenesis. The cytosine, guanine is unmethylated.

An “oligonucleotide delivery complex” is an oligonucleotide associated with (e.g. ionically or covalently bound to; or encapsulated within) a targeting means (e.g. a molecule that results in a higher affinity binding to a target cell (e.g. B cell or natural killer (NK) cell) surface and/or increased cellular uptake by target cells). Examples of oligonucleotide delivery complexes include oligonucleotides associated with: a sterol (e.g. cholesterol), a lipid (e.g. cationic lipid, virosome or liposome), or a target cell specific binding agent (e.g. a ligand recognized by a target cell specific receptor). Generally, the complexes must be sufficiently stable in vivo to prevent significant uncoupling prior to internalization by the target cell. However, the complex should be cleavable or otherwise accessible under appropriate conditions within the cell so that the oligonucleotide is functional. (Gursel, J. Immunol. 167:3324, 2001)

Operably linked: A first nucleic acid sequence is operably linked with a second nucleic acid sequence when the first nucleic acid sequence is placed in a functional relationship with the second nucleic acid sequence. For instance, a promoter is operably linked to a coding sequence, if the promoter affects the transcription or expression of the coding sequence. Generally, operably linked DNA sequences are contiguous and, where necessary to join two protein coding regions, in the same reading frame.

Pharmaceutical agent or drug: A chemical compound, nucleic acid molecule, or composition capable of inducing a desired therapeutic or prophylactic effect when properly administered to a subject. In one embodiment, a pharmaceutical agent induces angiogenesis or the production of VEGF.

Pharmaceutically acceptable carriers: The pharmaceutically acceptable carriers useful in this invention are conventional. Remington's Pharmaceutical Sciences, by E. W. Martin, Mack Publishing Co., Easton, Pa., 15th Edition (1975), describes compositions and formulations suitable for pharmaceutical delivery of the oligodeoxynucleotides herein disclosed.

In general, the nature of the carrier will depend on the particular mode of administration being employed. For instance, parenteral formulations usually comprise injectable fluids that include pharmaceutically and physiologically acceptable fluids such as water, physiological saline, balanced salt solutions, aqueous dextrose, glycerol or the like as a vehicle. For solid compositions (e.g., powder, pill, tablet, or capsule forms), conventional non-toxic solid carriers can include, for example, pharmaceutical grades of mannitol, lactose, starch, or magnesium stearate. In addition to biologically-neutral carriers, pharmaceutical compositions to be administered can contain minor amounts of non-toxic auxiliary substances, such as wetting or emulsifying agents, preservatives, and pH buffering agents and the like, for example sodium acetate or sorbitan monolaurate.

Polynucleotide: A linear nucleic acid sequence of any length. Therefore, a polynucleotide includes molecules which are 10, 15, 50, 100, 200 (oligonucleotides) and also nucleotides as long as a full length cDNA.

Portion (of a Nucleotide Sequence): At least 10, or 20, 30 or 40 nucleotides, in some cases, it would be advantageous to use a portion comprising 50 or more contiguous nucleotides of that specified nucleotide sequence (but no more than about a kilobase). A portion as used herein may includes a whole gene or a whole specified sequence, e.g., a portion of the DNA sequence of gene, or a portion of the DNA sequence of a virus. A portion may include as few as 10 nucleotides, or as many as 50 nucleotides or more, or a whole open reading frame, or the an entire gene of a viral genome, so long as the sequence comprises at least 10 nucleotides of the DNA sequence.

Purified: The term purified does not require absolute purity; rather, it is intended as a relative term. Thus, for example, a purified oligonucleotide preparation is one in which the oligodeoxynucleotide is more enriched than the protein is in its generative environment, for instance within a cell or in a biochemical reaction chamber. Preferably, a preparation of oligodeoxynucleotide is purified such that the oligodeoxynucleotide represents at least 50% of the total nucleotide content of the preparation.

Therapeutically effective dose: A dose sufficient to induce angiogenesis, or promote production of VEGF. In one embodiment, a therapeutically effective dose is an amount sufficient to relieve symptoms caused by the disease (e.g. atherosclerosis) or is sufficient to promote survival of a graft or cells transplanted into a subject.

Vascular Endothelial Growth Factor (VEGF): VEGF is a homodimeric heavily glycosylated protein of 46-48 kDa (24 kDa subunits). Glycosylation is not required, however, for biological activity. The subunits are linked by disulphide bonds. The human factor occurs in several molecular variants of 121 (VEGF-121), 165 (VEGF-165), 183 (VEGF-183), 189 (VEGF-189), 206 (VEGR-206) amino acids, arising by alternative splicing of the MRNA (for review see Neufeld et al., FASEB J. 13:9, 1999)

The human gene encoding VEGF has a length of approximately 12 kb and contains eight exons. Four species of MRNA encoding VEGF have been identified and found to be expressed in a tissue-specific manner. They arise from differential splicing with the 165 amino acid form of VEGF lacking sequences encoded by exon 6 and the 121 amino acid form lacking exon 6 and 7 sequences. The VEGF gene maps to human chromosome 6p12-p21.

VEGF is a highly specific mitogen for vascular endothelial cells. In vitro the two shorter forms of VEGF stimulate the proliferation of macrovascular endothelial cells. VEGF does not appear to enhance the proliferation of other cell types. VEGF significantly influence vascular permeability and is a strong angiogenic protein in several bioassays and probably also plays a role in neovascularization under physiological conditions. A potent synergism between VEGF and beta-FGF in the induction of angiogenesis has been observed. It has been suggested that VEGF released from smooth muscle cells and macrophages may play a role in the development of arteriosclerotic diseases.

VEGF can be assayed by an immunofluorometric test. An alternative and entirely different detection method is RT-PCR quantitation of cytokines. Methods for performing these assays are known (e.g. see Yeo et al., Clinical Chem. 38:71, 1992);

CpG ODN

A CpG oligodeoxynucleotide is an oligodeoxynucleotide including a CpG motif, wherein the pyrimdine ring of the cytosine is unmethylated. Two types of CpG ODNs have been identified: K type and D type ODNs. In one embodiment, the CpG ODN is in the range of about 8 to 30 bases in size. In another embodiment, the CpG ODN is at least 10 bases in size. For use in the methods disclosed herein, the nucleic acids can be synthesized de novo using any of a number of procedures well known in the art. For example, the b-cyanoethylphosphoramidite method (Beaucage et al., Tet. Let. 22:1859, 1981) or the nucleoside H-phosphonate method (Garegg et al., Tet. Let. 27:4051, 1986; Froehleret al., Nucl. Acid Res. 14:5399, 1986; Garegg et al., Tet. Let. 27:4055, 1986; Gaffiey et al., Tet. Let. 29:2619, 1988) can be utilized. These chemistries can be performed by a variety of automated oligonucleotide synthesizers available in the market.

Alternatively, CpG dinucleotides can be produced on a large scale in plasmids, (see Sambrook, et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory Press, New York, 1989) which after being administered to a subject are degraded into oligonucleotides. Oligonucleotides can be prepared from existing nucleic acid sequences (e.g., genomic or cDNA) using known techniques, such as those employing restriction enzymes, exonucleases or endonucleases (PCT/US98/03678).

For use in vivo, nucleic acids can be utilized that are relatively resistant to degradation (e.g., via endo-and exo-nucleases). Secondary structures, such as stem loops, can stabilize nucleic acids against degradation. Alternatively, nucleic acid stabilization can be accomplished via phosphate backbone modifications. In one embodiment, a stabilized nucleic acid has at least a partial phosphorothioate modified backbone. Phosphorothioates may be synthesized using automated techniques employing either phosphoramidate or H-phosphonate chemistries. Aryl- and alkyl-phosphonates can be made (e.g., as described in U.S. Pat. No. 4,469,863) and alkylphosphotriesters (in which the charged oxygen moiety isalkylated, as described in U.S. Pat. No. 5,023,243 and European Patent No. 092,574), and can be prepared by automated solid phase synthesis using commercially available reagents.

In one embodiment, the phosphate backbone modification occurs at the 5′ end of the nucleic acid. One specific, non-limiting example of a phosphate backbone modification is at the first two nucleotides of the 5′ end of the nucleic acid. In another embodiment, the phosphate backbone modification occurs at the 3′ end of the nucleic acid. One specific, non-limiting example of a phosphate backbone modification is at the last five nucleotides of the 3′ end of the nucleic acid.

Methods for making other DNA backbone modifications and substitutions have been described (Uhlmann et al., Chem. Rev. 90:544, 1990; Goodchild, Bioconjugate Chem. 1:1, 1990). 2′-O-methyl nucleic acids with CpG motifs also cause angiogenesis, as do ethoxy-modified CpG nucleic acids. In fact, no backbone modifications have been found that completely abolish the CpG effect, although it is greatly reduced by replacing the C with a 5-methyl C.

For administration in vivo, nucleic acids may be associated with a molecule that results in higher affinity binding to target cell (e.g., an endothelial cell) surfaces and/or increased cellular uptake by target cells to form a “nucleic acid delivery complex.” Nucleic acids can be ionically or covalently associated with appropriate molecules using techniques which are well known in the art (see below). Nucleic acids can alternatively be encapsulated in liposornes or virosomes using well-known techniques.

D and K type nucleic acids sequences of use are described in the published PCT Applications No. WO 98/18810A1 (K-type) and WO 00/61151 (D-type), which are incorporated by reference herein in their entirety.

A CpG ODN can be associated with (e.g., ionically or covalently bound to, or encapsulated within) a targeting moiety. Targeting moieties include any a molecule that results in higher affinity binding to a target cell, such as, but not limited to, an endothelial cell.

A variety of coupling or cross-linking agents can be used to form the delivery complex, such as protein A, carbodianide, and N-succinimidyl (2-pyridyldithio) propionate (SPDP). Examples of delivery complexes include CpG ODNs associated with a sterol (e.g., cholesterol), a lipid (e.g., a cationic lipid, virosome or liposome), and a target cell specific binding agent (e.g., a ligand recognized by target cell specific receptor). In one embodiment, the complexes are sufficiently stable in vivo to prevent significant uncoupling prior to internalization by the target cell. However, these complexes can be cleavable under appropriate circumstances such that the oligodeoxynucleotide can be released in a functional form (see WO 00/61151).

In another embodiment, fragments of viral or bacterial DNA can be used to produce CpG ODN, and thus to promote angiogenesis, and/or to induce the secretion of VEGF. Suitable DNA includes, but is not limited to, herpesviral DNA, such as HSV-1 or HSV-2 DNA. In one embodiment, fragmented Herpes Simplex Virus DNA is utilized as CpG ODNs. Specific non-limiting examples of fragmented viral DNA include, but are not limited to, viral DNA with an average length of ten bases, viral DNA with an average length of 100 bases, and viral DNA with an average length of 500 bases.

K ODN

In one embodiment, the CpG ODN is a K type ODN. Briefly, the K type nucleic acid sequences useful in the methods disclosed herein are represented by the formula:

5′-N₁DCGYN₂-3′ (SEQ ID NO: 2) wherein at least one nucleotide separates consecutive CpGs; D is adenine, guanine, or thymidine; Y is cytosine or thymine, N is any nucleotide and N₁+N₂ is from about 0-26 bases. In one embodiment, N₁ and N₂ do not contain a CCGG quadmer or more than one CGG trimer; and the nucleic acid sequence is from about 8-30 bases in length. However, nucleic acids of any size (even many kb long) can be used in the methods disclosed herein if CpGs are present. In one embodiment, synthetic oligonucleotides of use do not include a CCGG quadmer or more than one CCG or CGG trimer at or near the 5′ or 3′ terminals and/or the consensus mitogenic CpG motif is not a palindrome. A “palindromic sequence” or “palindrome” means an inverted repeat (i.e., a sequence such as ABCDEE′D′C′B′A′, in which A and A′ are bases capable of forming the usual Watson-Crick base pairs). An exemplary nucleic acid sequence is:

5′-ATAATCGACGTTCAAGCAAG-3′. (SEQ ID NO: 3) In another embodiment, the method of the invention includes the use of an oligodeoxynucleotide which contains a CpG motif represented by the formula:

5′-N₁RDCGYTN₂-3′ (SEQ ID NO: 4) wherein at least one nucleotide separates consecutive CpGs; RD is selected from the group consisting of GpT, GpG, GpA, ApT and ApA; YT is selected from the group consisting of TpT or CpT; N is any nucleotide and N₁+N₂ is from about 0-26 bases.

In one embodiment, N₁, and N₂ do not contain a CCGG quadmer or more than one CCG or CGG trimer. CpG ODN are also in the range of 8 to 30 bases in length, but may be of any size (even many kb long) if sufficient motifs are present. In one embodiment, synthetic oligodeoxynucleotides of this formula do not include a CCGG quadmer or more than one CCG or CGG trimer at or near the 5′ and/or 3′ terminals and/or the consensus CpG motif is not a palindrome. Other CpG oligodeoxynucleotides can be assayed for efficacy using methods described herein. It should be noted that exemplary K-type oligodeoxynucleotides are known in the art, and have been fully described, for example in WO 98/18810A1.

D ODN

In another embodiment, the CpG ODN is a “D type” CpG ODN (see Verthelyi et al, J. Immunol. 166:2372, 2001; published PCT Application No. WO 00/61151, both of which show sequences of representative D ODN, and both of which are herein incorporated by reference in their entirety). In one embodiment, a “D type” CpG ODN comprises multiple different CpG sequences with at least one of the multiple different CpG sequences represented by the formula:

5′ N₁N₂N₃T-CpG-WN₄N₅N₆ Y, (SEQ ID NO: 5) wherein W is A or T, and N₁, N₂, N₃ N₄, N₅, and N₆ are any nucleotides or the formula 5′ RY-CpG-RY T, wherein R is A or G and Y is C or T.

Alternatively, different sequences can be represented by the formula: 5′ RY-CpG-RY-3′ wherein R is A or G and Y is C or T.

In one embodiment, a D type ODN is at least about 16 nucleotides in length and includes a sequence represented by the following formula:

5′-N₁N₂N₃ R₁ Y₂ CpG R₃ Y₄ N₄N₅N₆(N)_(x) (SEQ ID NO: 6) (G)_(z)-3′

wherein the central CpG motif is unmethylated, R is a purine nucleotide, Y is a pyrimidine nucleotide, N is any nucleotide, X is any integer from 0 to 10, and Z is any integer from 4 to 10.

The region R₁ Y₂ CpG R₃ Y₄ is termed the CpG motif. The region N₁N₂N₃ is termed the 5′ flanking region, and the region N₄N₅N₆ is termed the 3′ flanking region. If nucleotides are included 5′ of N₁N₂N₃ in the D ODN these nucleotides are termed the 5′ far flanking region. Nucleotides 3′ of N₄N₅N₆ in the D ODN are termed the 3′ far flanking region.

In one specific non-limiting example, Y₂ is a cytosine. In another specific, non-limiting example, R₃ is a guanidine. In yet another specific, non limiting example, Y₂ is a thymidine and R₃ is an adenine. In a further specific, non-limiting example, R₁ is an adenine and Y₂ is a tyrosine. In another specific, non-limiting example, R₃ is an adenine and Y₄ is a tyrosine.

In one specific not limiting example, Z is from about 4 to about 8. In another specific, non-limiting example, Z is about 6.

D-type CpG oligodeoxynucleotides can include modified nucleotides. Without being bound by theory, modified nucleotides can be included to increase the stability of a D-type oligodeoxynucleotide. Without being bound by theory, because phosphorothioate-modified nucleotides confer resistance to exonuclease digestion, the D ODN are “stabilized” by incorporating phosphorothioate-modified nucleotides. In one embodiment, the CpG dinucleotide motif and its immediate flanking regions include phosphodiester rather than phosphorothioate nucleotides. In one specific non-limiting example, the sequence R₁ Y₂ CpG R₃ Y₄ includes phosphodiester bases. In another specific, non-limiting example, all of the bases in the sequence R₁ Y₂ CpG R₃ Y₄ are phosphodiester bases. In yet another specific, non-limiting example, N₁N₂N₃ and N₄N₅N₆(N)_(x)(G)_(z) include phosphodiester bases. In yet another specific, non-limiting example, N₁N₂N₃ R₁ Y₂ CpG R₃ Y₄ N₄N₅N₆(N)_(x) (G)_(z) include phosphodiester bases. In further non-limiting examples, the sequence N₁N₂N₃ includes at most one or at most two phosphothioate bases and/or the sequence N₄N₅N₆ includes at most one or at most two phosphotioate bases. In additional non-limiting examples, N₄N₅N₆(N)_(x) (G)_(z) includes at least 1, at least 2, at least 3, at least 4, or at least 5 phosphothioate bases. Thus, a D type oligodeoxynucleotide can be a phosphorothioate/phosphodiester chimera.

Any suitable modification can be used to render the D oligodeoxynucleotide resistant to degradation in vivo (e.g., via an exo- or endo-nuclease). In one specific, non-limiting example, a modification that renders the oligodeoxynucleotide less susceptible to degradation is the inclusion of nontraditional bases such as inosine and quesine, as well as acetyl-, thio- and similarly modified forms of adenine, cytidine, guanine, thymine, and uridine. Other modified nucleotides include nonionic DNA analogs, such as alkyl or aryl phosphonates (i.e., the charged phosphonate oxygen is replaced with an alkyl or aryl group, as set forth in U.S. Pat. No. 4,469,863), phosphodiesters and alkylphosphotriesters (i.e., the charged oxygen moiety is alkylated, as set forth in U.S. Pat. No. 5,023,243 and European Patent No. 0 092 574). Oligonucleotides containing a diol, such as tetraethyleneglycol or hexaethyleneglycol, at either or both termini, have also been shown to be more resistant to degradation. The D type oligodeoxynucleotides can also be modified to contain a secondary structure (e.g., stem loop structure). Without being bound by theory, it is believed that incorporation of a stem loop structure renders an oligodeoxynucleotide more effective.

In a further embodiment, R₁ Y₂ and R₃ Y₄ are self complementary. In another embodiment, N₁N₂N₃ andN₄N₅N₆ are self complementary. In yet another embodiment, N₁N₂N₃ R₁ Y₂ and R₃ Y₄ N₄N₅N₆ are self complementary.

Specific non-limiting examples of a D type oligodeoxynucleotide wherein R₁ Y₂ and R₃ Y₄ are self complementary include, but are not limited to, ATCGAT, ACCGGT, ATCGAC, ACCGAT, GTCGAC, or GCCGGC. Without being bound by theory, the self complementary base sequences can help to form a stem-loop structure with the CpG dinucleotide at the apex to facilitate immunostimulatory functions. Thus, in one specific, non-limiting example, D type oligodeoxynucleotides wherein R₁ Y₂ and R₃ Y₄ are self-complementary induce higher levels of IFN-γ production from a cell of the immune system (see below). The self complementary need not be limited to R₁ Y₂ and R₃ Y₄. Thus, in another embodiment, additional bases on each side of the three bases on each side of the CpG-containing hexamer form a self complementary sequence (see above).

It should be noted that exemplary D type oligodeoxynucleotides are well known in the art, for example as described in WO 00/61151.

Pharmacologic Compositions and Therapeutic Use

CpG ODNs can be used to promote angiogenesis and/or to induce production of an angiogenic factor, in vivo or in vitro. In one embodiment, the factor is a factor modulating growth, chemotactic behavior and/or a functional activity of vascular endothelial cells. Specific, non-limiting examples of angiogenic factors include, but are not limited to, aFGF, bFGF, angiogenein, angiotropin, epithelial growth factor, IL-8, and vascular endothelial growth factor (VEGF), amongst others. For example, CpG ODN is used to induce the production of VEGF, and/or promote angiogenesis.

In one embodiment, a CpG ODN is administered to a cell or a tissue culture in vitro. In another embodiment, cells or a tissue treated with CpG ODN are transplanted into a subject. In one specific, non-limiting example, CpG ODNs are administered to a graft, such as a skin graft, prior to transplantation. In one specific, non-limiting example, CpG ODNs are administered to an organ, such as a heart, lung, or kidney, prior to transplantation.

In one embodiment, the CpG ODN is administered with a second angiogenic factor. Specific, non-limiting examples of angiogenic factors of use include, but are not limited to aFGF, bFGF, platelet derived endothelial cell growth factor, angiogenein, angiotropin, epithelial growth factor, and IL-8.

In another embodiment, CpG ODN are utilized in vivo. Thus, a therapeutically effective amount of a CpG ODN and a pharmacologically acceptable carrier are administered to a subject, such that cells of the subject produce VEGF. In addition, a therapeutically effective amount of a CpG ODN and a pharmacologically acceptable carrier can be administered to a subject to promote angiogenesis. Suitable subjects include, but are not limited to, subjects with a graft (e.g., a skin graft), subjects who exhibit male pattern baldness, or subjects who have a wound, in order to promote wound healing. Suitable subjects also include those with atherosclerosis. Additional agents that promote angiogenesis are known in the art, and can be administered in conjunction with a CpG ODN.

Additional applications for in vivo use include vascularization of ischemic tissue such as ischemic heart tissue and ischemic peripheral tissue, and vascularization of chronic wounds, burns and transplanted tissue. In one example, the CpG ODN is administered (either systemically or locally) to a subject undergoing transmyocardial laser revascularization. In yet other examples, the CpG ODN are administered to animals to promote inappropriate neovascularization to provide an animal model of inappropriate neovascularization (see below and see Example 1). The animal model then can be used to study treatments to induce regression of vascularization (such as the administration of potential drugs to induce regression of pathological neovascularization).

Pharmacologically acceptable carriers (e.g., physiologically or pharmaceutically acceptable carriers) are well known in the art, and include, but are not limited to buffered solutions as a physiological pH (e.g. from a pH of about 7.0 to about 8.0, or at a pH of about 7.4). One specific, non-limiting example of a physiologically compatible buffered solution is phosphate buffered saline. Other pharmacologically acceptable carriers include penetrants, which are particularly suitable for pharmaceutical formulations that are intended to be topically applied (for example in the application of surgical wounds to promote healing).

The pharmacological compositions disclosed herein facilitate the use of CpG ODN, both in vivo and ex vivo, to promote angiogenesis and/or induce the production of VEGF. Such a composition can be suitable for delivery of the active ingredient to any suitable subject, and can be manufactured in a manner that is itself known, e.g., by means of conventional mixing, dissolving, granulating, emulsifying, encapsulating, entrapping or lyophilizing processes. Pharmacological compositions can be formulated in a conventional manner using one or more pharmacologically (e.g., physiologically or pharmaceutically) acceptable carriers, as well as optional auxiliaries that facilitate processing of the active compounds into preparations which can be used pharmaceutically. Proper formulation is dependent upon the route of administration chosen. Thus, for injection, the active ingredient can be formulated in aqueous solutions. For transmucosal administration, penetrants appropriate to the barrier to be permeated are used in the formulation. Such penetrants are generally known in the art.

For oral administration, the active ingredient can be combined with carriers suitable for incorporation into tablets, pills, capsules, liquids, gels, syrups, slurries, suspensions and the like. For administration by inhalation, the active ingredient is conveniently delivered in the form of an aerosol spray presentation from pressurized packs or a nebuliser, with the use of a suitable propellant. The active ingredient can be formulated for parenteral administration by injection, e.g., by bolus injection or continuous infusion. Such compositions can take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and can contain formulatory agents such as suspending, stabilizing and/or dispersing agents. Other pharmacological excipients are known in the art.

Optionally, the ODN can be contained within or conjugated with a protein, hydrocarbon or lipid, whether for in vitro or in vivo administration. Once this molecule is administered, the ODN sequence must be exposed on the surface to induce production of VEGF and/or angiogenesis. The CpG ODN can also be co-administered with a protein, hydrocarbon, or lipid. Co-administration can be such that the CpG ODN is administered before, at substantially the same time as, or after the protein, hydrocarbon, or lipid. In one embodiment, the ODN is administered at substantially the same time, as the protein, hydrocarbon, or lipid.

Other delivery systems can include time-release, delayed release or sustained release delivery systems. Such systems can avoid repeated administrations of the compositions of the invention described above, increasing convenience to the subject and the physician. Many types of release delivery systems are available and known to those of ordinary skill in the art. They include polymer based systems such as poly(lactide-glycolide), copolyoxalates, polycaprolactones, polyesteramides, polyorthoesters, polyhydroxybutyric acid, and polyanhydrides. Microcapsules of the foregoing polymers containing drugs are described in, for example, U.S. Pat. No. 5,075,109. Delivery systems also include non-polymer systems, such as lipids including sterols such as cholesterol, cholesterol esters and fatty acids or neutral fats such as mono- di- and tri-glycerides; hydrogel release systems; silastic systems; peptide based systems; wax coatings; compressed tablets using conventional binders and excipients; partially fused implants; and the like. Specific examples include, but are not limited to: (a) erosional systems in which the compositions of the invention is contained in a form within a matrix such as those described in U.S. Pat. Nos. 4,452,775; 4,667,014; 4,748,034; 5,239,660; and 6,218,371 and (b) difusional systems in which an active component permeates at a controlled rate from a polymer such as described in U.S. Pat. Nos. 3,832,253 and 3,854,480. In addition, pump-based hardware delivery systems can be used, some of which are adapted for implantation.

Use of a long-term sustained release implant may be particularly suitable for treatment of chronic conditions, such as to promote graft survival or to treat baldness. Long-term release, as used herein, means that the implant is constructed and arranged to deliver therapeutic levels of the active ingredient for at least 30 days, and preferably 60 days. Long-term sustained release implants are well known to those of ordinary skill in the art and include some of the release systems described above. These systems have been described for use with CpG ODNs (see U.S. Pat. No. 6,218,371). For use in vivo, nucleic acids are preferably relatively resistant to degradation (e.g. via endo- and exo-nucleases). Thus, modifications, such as phosphate backbone modifications (see above) can be utilized to promote stabilization.

Screening Methods

A method is provided herein for screening for an agent that inhibit neovascularization. The method includes administering a CpG ODN to a non-human mammal. The animal can be any mammal, including, but not limited to, mice, rats, or rabbits. However, the use of any veterinary animal is contemplated, including both domestic (e.g., cats, dogs, guinea pigs, hamsters, etc.) and farm (e.g. cows, sheep, pigs, etc.) is contemplated. In one embodiment, the CpG ODN is administered to the cornea. However, administration can be to any tissue where angiogenesis can be assessed.

The method also includes administering a potentially therapeutically effective amount of the agent to the non-human mammal. Suitable agents include, but are not limited to, peptides, cytokines, chemokines, small molecules, chemical compounds, known pharmaceutical agents, afitisense molecules, ribozymes, or any other molecules of interest. Inhibition of angiogenesis in the non-human animal indicates that the agent is effective in inhibiting neovascularization.

In one specific, non-limiting example, angiogenesis in the non-human animal treated with the agent is compared to a control. Suitable controls include, but are not limited to angiogenesis in a non-human animal treated with the CpG ODN, but not treated with the agent. Suitable controls also include a standard value, or an non-human animal treated with the CpG ODN, and treated with an agent know to inhibit angiogenesis.

The invention is illustrated by the following non-limiting Examples.

EXAMPLES Example 1 Materials and Methods

Reagents

Phosphorothioate ODNs were synthesized at the Center for Biologics Evaluation and Research core facility, as previously described (Verthelyi et al., J Immunol., 166:2372-2377, 2001). The sequences of the stimulatory ODNs used in this study were: ODN 1466, having the sequence TCAACGTTGA (SEQ ID NO: 7) and ODN 1555 having the sequence GCTAGACGTTAGCGT. (SEQ ID NO: 8). The control ODN 1471 had the sequence TCAAGCTTGA (SEQ ID NO: 9). There was no detectable endotoxin contamination in any of the ODNs, as monitored by LAL assay (Bio Whittaker, Inc., Walkersville, Md.). In some experiments, FITC was conjugated to the 5′ end of these ODNs to monitor their distribution in vivo.

Herring sperm DNA (Boehringer Mannheim, Mannheim, Germany) was prepared by passage through Detoxi-Gel™ Endotoxin Removal Gel 20344 (PcPierce, Rockford, Ill.) to reduce endotoxin levels to <6 EU/mg. Recombinant human VEGF165 (rhVEGF), recombinant mouse VEGF (rmVEGF), mouse VEGF neutralizing antibody and biotinylated rat-anti-mouse VEGF were purchased from R & D Systems Inc. (Minneapolis, Minn.). Synthetic mesh and hydron polymer (type NCC) were purchased from Sefar America Inc. (Kansas City, Mo.) and Hydro Med Sciences, respectively. Sucralfate was provided by Bulch Meditec (Vaerlose, Denmark). Lipopolysacharride (LPS) was purchased from Sigma (St. Louis, Mo.) and streptavidin-PE from Pharmingen (San Diego, Calif.).

Isolation of HSV-1 DNA

Virus was harvested from infected Vero cells when the cytopathic effects were maximal by centrifugation at 1000 g for 30 minutes at 4° C. (Klinman et al., Proc Natl Acad Sci USA, 93:2879-83, 1996). Cells were suspended in sterile PBS and freeze-thawed three times to release viral particles. The virion-containing supernatant was then ultracentrifuged at 25,000 g for 90 minutes at 4° C., and the pellet suspended in sterile phosphate buffered saline (PBS). Viral particles were precipitated in a solution of 7% polyethylene glycol 8000 in 2.3% NaCl overnight at 4° C. DNA was isolated from virions by treatment with 200 ug/ml proteinase K and 1% sarcosyl in STE buffer overnight at 56° C. The DNA was purified by multiple phenol:chloroform:isoamyl alcohol extractions, precipitated, dried, and re-suspended in sterile STE buffer. RNA was removed by incubation with RNase (100 mg/ml; 5 Prime˜3 Prime, Inc.) for 1 hour at 37° C., and the DNA re-extracted as described above. All procedures were performed in a sterile environment and all buffers and solutions were checked for the presence of LPS using the Pyrogent plus test. There was no detectable protein, viral RNA, or cellular DNA and less than 0.06 EU of endotoxin per mg of HSV DNA.

Mice

Female BALB/c (Harlan Sprague Dawley, Indianapolis, Ind.) were used for all experiments. Animals were housed and cared for as described elsewhere (Gangappa et al., J Immunol. 161:4289-4300, 1998).

Corneal Micropocket Assay

The murine corneal micropocket assay used in this work followed the general protocol of Kenyon et al., Invest Ophthalmol Vis Sci, 37:1625-1632, 1996. Pellets 0.4×0.4×0.2 mm³ composed of sucralfate and hydron polymer were prepared (Kenyon et al., Invest Ophthalmol Vis Sci, 37: 625-1632, 1996). Known amounts of VEGF and DNA were added to these pellets prior to insertion into comeal pockets. The micropockets were placed 0.6-0.8 mm from the limbus (in the pericenter of the cornea at the lateral canthus of the eye) under stereomicroscopy (4 eyes/group). In some experiments, anti-mVEGF neutralizing antibody (5 μg in 5 μl of PBS) was injected subconjunctivally into the eyes of recipient mice just prior to and 2 days after pellet implantation.

Angiogenesis was quantitated at multiple times post pellet implantation under stereomicroscopy. Briefly, the length of the neovessels (in mm) generated from the limbal vessel ring toward the center of the cornea and the width of the neovessels presented in clock hours (each clock hour is equal to 30° C. at the circumference) was measured (Zheng et al., Am J Pathol. 159:1021-1029, 2001). The angiogenic area was calculated according to the formula for an ellipse. A=[(clock hours)×0.4×(vessel length in mm)×π]/2.

Immunohistochemical Staining

Eyes were removed and snap frozen in OCT compound (Miles Elkhart, Ind.). 6 μm sections were cut, air dried, and fixed in cold acetone for 10 minutes. The sections were blocked with 3% BSA and stained with biotinylated anti-mVEGF164. Sections were then treated with horseradish peroxidase-conjugated streptavidin (1:1000) and 3,3′-diaminobenzidine (Vector, Burlingame, Calif.) and counterstained with hematoxylin as previously described (Sparwasser et al., Eur. J. Immunol. 28:2045-2054, 1998). Cellular infiltration was determined microscopically by counting the infiltrating cells in the corneal stroma. Each data point represents the mean total cellular infiltrate in four central corneal sections from two eyes.

VEGF Staining of J774A.1 Cells

J774A.1 cells were plated and incubated in two-well chamber slides (Lab-Tek, Nalge Nunc International, Naperville, Ill.) or in 24-well plates (for later RT-PCR) in DMEM with 10% FBS overnight at 37° C. in 5% CO₂. The cells in chamber slides were co-cultured with FITC-labeled CpG ODN (1555) or control ODN (1471) at a concentration of 2 μg/10⁶ cells. The cells were washed twice with PBS and fixed in a 1:1 mixture of acetone:methylalcohol at −20° C. for 15 minutes. The cells were stained with biotinylated rat-anti-mVEGF 6-18 hours post ODN stimulation and subsequently reacted with streptavidin-PE. Images were taken using a fluorescence microscope (Hamamatsu, Japan). The cells in 24-well plates were treated with 2 μg of ODN per 10⁶ cells/ml. RNA from these cells was extracted for RT-PCR to detect VEGF MRNA (see RT-PCR methods section).

FA CS Staining of VEGF Expressing Cells

J774A.1 cells were treated with 0-8 μg/ml of ODN for 6-12 hours. The cells were then fixed in paraformaldehyde, blocked with FCS, and stained for VEGF using biotinylated rat-anti- mVEGF164 antibody followed by streptavidin-PE. Positive cells were identified by flow cytometry.

RNA Extraction and RT-PCR

10⁶ J774A.1 cells were cultured with 2 μg of ODN for 3-6 hours. The cells were harvested in Tri-reagent (Molecular Biology Inc., Cincinnati, Ohio) and total RNA extracted as recommended by the manufacturer. Total RNA (10 μg) was reverse transcribed and aliquots of cDNA were used in a 25:1 PCR reaction as previously described (Takeshita et al., Neuroreport., 12:3029-3032, 2001). The amplification profile was 94° C. for 1 minute, 65° C. for 1 minute, and 72° C. for 15 minutes for 30 cycles. The primer sequences for VEGF were:

-   5′-GCGGGCTGCCTCGCAGTC-3′ (sense, SEQ ID NO: 10) and -   5′-TCACCGCCTTGGCTTGTCAC-3′ (antisense, SEQ ID NO: 11), respectively.     RT-PCR products were 716 bp (mVEGF188), 644 bp (mVEGF164) and 512 bp     (mVEGF120), respectively.     Statistical Analysis

Significant differences between groups were evaluated using the Student's t test. P≦0.05 was regarded as significant difference between two groups.

Example 2 Purified Herpes Simplex Virus DNA Stimulates Angiogenesis

HSV infection of mice can result in the blinding neovascular comeal lesions of stromal keratitis (SK) (1-3). To determine whether viral DNA plays a role in the pathogenesis of these lesions, DNA was purified from HSV infected cells. The HSV DNA was introduced into hydron pellets and surgically inserted into corneal micropockets established in the eyes of BALB/c mice. New blood vessel formation in the corneal limbus (emanating from the margin of the limbal vessel ring) was monitored daily. Initial experiments showed that HSV DNA elicited significant angiogenesis, as did pellets containing VEGF protein, but not those containing control herring sperm DNA (FIG. 1).

Dose response studies established that 90 ng of rhVEGF and 2 μg of HSV DNA triggered significant blood vessel formation (FIGS. 1 and 2). Angiogenesis developed within 24 hours of implantation, with the magnitude of new blood vessel formation progressing until the experiment was terminated on day 4. HSV DNA induced approximately half as much angiogenesis as did purified VEGF (FIG. 1), significantly exceeding the effect of empty hydron pellets or pellets containing control DNA (see FIG. 1).

Example 3 CpG DNA Induces Angiogenesis

The DNA sequence of HSV was analyzed to identify potentially pro-angiogenic motifs. Of interest, the frequency of bioactive CpG motifs present in the HSV genome was similar to that of bacterial DNA and was much higher than vertebrate DNA (Table 1).

TABLE 1 CpG expression frequency in HSV-1 versus murine DNA* Expression frequency Motif E. coli Mouse HSV-1 Fold difference GACGTT 1.3 0.11 0.82 7.5 AGCGTT 1.7 0.17 0.46 2.7 AACGTC 0.6 0.11 0.81 7.4 AGCGTC 1.3 0.15 0.95 6.3 GGCGTC 1.4 0.15 4.50 30.0 GGCGTT 2.5 0.15 1.68 11.2 Average 1.53 0.14 1.54 11.0 *The frequency with which each CpG hexamer is expressed in the genome of E. coli, mice and HSV-1 was determined using published sequence data (The mouse chromosome data was a composite of chromosomes 1-3. The GenBank accession numbers for mouse chromosome 1, 2 and 3 are: NT_025524, NT_019187 and NT_015485, respectively.The GenBank accession numbers for E. coli-K12 and for the HSV-1 complete genome are NC_000913 and X14112, respectively.). Note the significant over-expression of immunostimulatory GCGTC and GCGTT motifs in the HSV genome versus that of the mouse (fold difference).

To determine whether these CpG motifs (which are known to activate cells of the immune system and central nervous system) contribute to HSV-dependent angiogenesis, hydron pellets were infused with synthetic oligodeoxynucleotides (ODN) expressing CpG motifs. Pellets containing ≧1 ug of CpG ODN induced significant levels of angiogenesis (approximately 75% of that elicited by an optimal concentration of VEGF). The kinetics of new blood vessel formation induced by CpG ODN was indistinguishable from that of HSV DNA (FIG. 2). In contrast, the effect of control ODN (in which the CpG motif was eliminated by inversion) did not differ from empty hydron pellets (FIG. 2).

Example 4 Production of VEGF Characterizes CpG DNA Induced Angiogenesis

Based on previous evidence that HSV-associated angiogenesis involved the production of VEGF (Zheng et al., J Virol. 75:9828-9838, 2001) the ability of CpG DNA to stimulate VEGF secretion was evaluated. Histologic analysis of the region surrounding the comeal micropockets of animals treated with CpG DNA (both HSV DNA and CpG ODN) revealed that numerous inflammatory cells had infiltrated the site of pellet implantation (FIG. 3C, p≦0.01). These were primarily polymorphonuclear leukocytes and macrophages. Staining these sections with anti-VEGF Ab revealed that the infiltrating cells were producing VEGF protein (FIG. 3). Staining these sections with anti-VEGF antibody revealed that the infiltrating cells, and cells in the epithelium of eyes treated with CpG ODN, were producing VEFG protein (FIG. 3A). Significantly fewer VEGF expressing cells were present in the eyes of mice treated with control ODN or empty pellets (FIGS. 3A, 3B).

To determine whether the VEGF being produced by cells at the site of CpG DNA administration contributed to new blood vessel formation, neutralizing anti-VEGF antibody was administered subconjunctivally to these mice. As seen in FIG. 4, anti-VEGF Ab inhibited the angiogenesis induced by HSV DNA, CpG ODN and VEGF by approximately 70%. In contrast, anti-VEGF Ab had no effect on the background levels of angiogenesis observed using empty pellets or those containing control ODN.

Example 5 CpG DNA Stimulates VEGF Expression In Vitro

To verify that CpG DNA directly induced cells to produce VEGF, the J774A.1 murine macrophage cell line (which is known to produce VEGF when infected with HSV) was treated in vitro with 1-3 μg of HSV-DNA or herring sperm DNA, CpG or control ODN. As seen in FIG. 5, mRNA encoding the 120 isotype of VEGF was up-regulated within 3 hours of treatment with CpG but not control ODN. By 6 hours, expression of both the 120 and 164 isoforms of VEGF was induced by CpG ODN. In contrast, cells cultured in medium alone, or with control ODN, expressed minimal levels of VEGF mRNA.

A second series of experiments measured the production of VEGF protein by J774A.1 cells stimulated with CpG ODN. Fewer than 0.3% of untreated J774A.1 cells scored positive for VEGF protein (Table 2). The number of VEGF expressing cells increased within 6 hours of CpG ODN stimulation, with 20-26% of cells treated with 3 μg/ml CpG ODN producing protein at 24 hours (Table 2).

TABLE 2 Expression of VEGF following exposure of J774A.1 cells to CpG DNA Dose % VEGF positive cells Treatment (ug/ml) 6 h 24 h CpG ODN 0.1 0.3 1.2 1.0 9.1 21.7 3.0 10.1 26.2 8.0 12.6 15.3 Control ODN 3.0 4.5 5.3 Media 0.1 0.3 J774A.1 cells were treated in vitro with 0.1-8.0 ug/ml of CpG ODN for 6 or 24 h. Cells expressing VEGF were identified by staining with rat-anti- mVEGF antibody (Ab). Results are representative of three independent experiments.

This significantly exceeded the number of cells triggered to produce VEGF by control ODN. To determine whether VEGF production correlated with CpG ODN uptake, cultures were stimulated with fluorescein-labeled CpG ODN and simultaneously monitored for VEGF expression. All VEGF producing cells stained positive for CpG ODN, suggesting that CpG DNA directly triggered these cells to produce this angiogenic protein (FIG. 6).

Neovascularization anywhere along the visual axis poses a threat to ocular function. HSV infection of the eye is associated with new blood vessel formation in the normally avascular cornea (Zheng et al., J Virol., 75:9828-9835, 2001; Zheng et al., Am J Pathol, 159:1021-1029, 2001). The molecular mechanism(s) underlying this effect are poorly defined, although evidence suggests that VEGF (a highly potent pro-angiogenic host protein (Ferrara, Nature, 380:439-442, 1996; Ferrara, Curr. Top. Microbio. Immunol., 327:1-30, 1999; Yancopoulos, Nature, 407:242-248, 2000) is involved, at least indirectly (Zheng et al., J Virol., 75:9828-9835, 2001). The work disclosed herein provides evidence that HSV DNA, likely through its content of bioactive CpG motifs, contributes to virus-induced ocular angiogenesis. Without being bound by theory, these findings provide a mechanism by which HSV infection induces angiogenesis during herpetic stromal keratitis.

CpG ODN express a wide range of biological activities. They are potent vaccine adjuvants, anti-allergens, and trigger an protective innate immune response (Klinman, Antisense Nucleic Acid Drug Dev., 8:181-184, 1998; Davis et al., J Immunol, 160:870-876, 1998; Broide et al., J Immunol, 161:7054-7062, 1998; Krieg et al., J Immunol, 161:2428-2434, 1998). Several recent reports indicate that CpG ODN also stimulate cells of the central nervous system (Takeshita et al., Neuroreport, 12:3029-3032, 2001). Although CpG ODN have many potential uses, their potential to induce angiogenesis has not been previously recognized. The experiments disclosed herein document that bioactive CpG motifs induce dose-dependent neovascularization in the corneas of mice engrafted with hydron pellets containing CpG ODN or HSV DNA. The degree of angiogenesis elicited by an optimal amount of CpG ODN was approximately 75% of that induced by the potent angiogenic factor VEGF. This activity was motif specific, since ODN in which the critical CpG dinucleotide was inverted to a GpC lacked function.

Without being bound by theory, the results suggest that, rather than triggering new blood vessel formation directly, CpG motifs stimulate host cells to secrete VEGF, which in turn induces neovascularization. Several findings are consistent with this model. First, CpG ODN were taken up by the same inflammatory cells that expressed VEGF. Second, exposure to CpG motifs directly stimulated J774A.1 murine macrophages to produce VEGF. Finally, local administration of anti-VEGF antibodies to CpG DNA treated eyes significantly inhibited corneal angiogenesis.

These studies were undertaken to elucidate the mechanism by which ocular infection with HSV causes angiogenesis, an essential event in the pathogenesis of herpetic stromal keratitis (Zheng et al., J Virol., 75:9828-9835, 2001; Zheng et al., Am J Pathol, 159:1021-1029, 2001). The HSV genome has a codon usage that favors C and G (Roizman, Cell 16:481-494, 1979). In consequence the HSV genome contains a significantly higher frequency of bioactive CpG motifs than does vertebrate DNA (Table 1). This pattern of CpG expression is reminiscent of bacterial DNA, which has well-established pro-inflammatory effects (Krieg et al., Nature, 374:546-549, 1995; Klimnan et al., Proc Natl Acad Sci USA, 93:2879-2883, 1996). The results disclosed herein expand the list of activities mediated by CpG DNA to include angiogetiesis and the induction of VEGF secretion.

Example 6 Animal Model for Identifying Agents that Inhibit Angiogenesis

Neovascular diseases are a serious problem in the eye. For example, in retinal diseases such as diabetic retinopathy and macular degeneration, inappropriate vascularization of the retina is part of the pathogenic process that can lead to blindness. In addition, neovascularization of the cornea is a serious problem in chronic inflammatory conditions of the eye, such as Herpes Simplex infection and corneal transplant rejection. Clearly, there is a need to identify agents that inhibit in appropriate pathological neovascularization in the eye.

Thus, in one embodiment, an animal model of neovascularization in the eye is provided. In this model system CpG ODN are administered to an area of the eye to induce neovascularization. Potential therapeutic agents of interest are administered to the animal model in order to identify agents that inhibit vascularization, or reverse existing neovascularization. Specific, non-limiting examples of agents of interest include photodynamic therapy agents (see U. S. Pat. No. 6,225,303) and steroids (e.g. see U.S. Pat. No. 5,929,111), amongst others (see published PCT Application No. WO 90/04409A). In one embodiment, induced neovascularization in an animal to which the potentially therapeutic agent has been administered is compared with a control animal to which the potentially therapeutic agent has not been administered.

In one embodiment, a corneal micropocket assay is utilized (see Example 1 and Kenyon et al., Invest Ophthalmol Vis Sci, 37:1625-1632, 1996. Pellets 0.4×0.4×0.2 mm³ are composed of sucralfate and hydron polymer are prepared (Sparwasser et al., Eur. J Immunol 27:1671-1679, 1997). Known amounts of DNA are added to these pellets prior to insertion into corneal pockets. The micropockets are placed 0.6-0.8 mm from the limbus (in the pericenter of the cornea at the lateral canthus of the eye) under stereomicroscopy (4 eyes/group). One group of animals is transplanted with pellets including CpG ODN, and is treated with an agent of interest, while a second group of animals is transplanted with pellets including CpG ODN, but are not treated with the agent of interest. The agent of interest can be administered at the time of transplantation, or can be administered subsequent to transplantation.

Angiogenesis is quantitated at multiple times post pellet implantation under stereomicroscopy. Briefly, the length of the neovessels (in mm) generated from the limbal vessel ring toward the center of the cornea and the width of the neovessels presented in clock hours (each clock hour is equal to 30° C. at the circumference) is measured (Zheng et al., J Virol, 75:9828-9835, 2001), and the angiogenic area is calculated as described in Example 1. The angiogenic area of the animals treated with the agent of interest is then compared to the angiogenic area of the control animals. An agent is identified as being of interest (e.g. “anti-angiogenic”) if the angiogenic area is decreased by at least 25%, at least 50%, at least 75:, or at least 90%.

Example 7 ODN Sequences

Exemplary K ODN, D ODN, K ODN control, and D ODN control sequences are listed below in Table 1.

TABLE 3 SEQUENCE ODN SEQUENCE IDENTIFIER D ODN DV104 GGTGCATCGATGCAGGGGGG (SEQ ID NO: 12) DV19 GGTGCATCGATGCAGGGGGG (SEQ ID NO: 12) DV29 GGTGCACCGGTGCAGGGGGG (SEQ ID NO: 13) DV35 GGTGCATCGATGCAGGGGGG (SEQ ID NO: 12) DV28 GGTGCGTCGATGCAGGGGGG (SEQ ID NO: 14) DV106 GGTGTGTCGATGCAGGGGGG (SEQ ID NO: 15) DV116 TGCATCGATGCAGGGGGG (SEQ ID NO: 16) DV113 GGTGCATCGATACAGGGGGG (SEQ ID NO: 17) DV34 GGTGCATCGATGCAGGGGGG (SEQ ID NO: 12) DV102 GGTGCATCGTTGCAGGGGGG (SEQ ID NO: 18) DV32 GGTGCGTCGACGCAGGGGGG (SEQ ID NO: 19) DV117 GGTCGATCGATGCACGGGGG (SEQ ID NO: 20) DV37 GGTGC ATCGAT GCAGGGGGG (SEQ ID NO: 12) DV25 GGTGCATCGATGCAGGGGGG (SEQ ID NO: 12) DV30 GGTGCATCGACGCAGGGGGG (SEQ ID NO: 21) dv120 GGTGCATCGATAGGCGGGGG (SEQ ID NO: 22) DV27 GGTGCACCGATGCAGGGGGG (SEQ ID NO: 23) dv119 CCTGCATCGATGCAGGGGGG (SEQ ID NO: 24) D142 GGTATATCGATATAGGGGGG (SEQ ID NO: 25) d143 GGTGGAT CG ATCCAGGGGGG (SEQ ID NO: 26) D CONTROLS dv17 GGTGCAACGTTGCAGGGGGG (SEQ ID NO: 27) DV78 GGTGCATCGATAGAGGGGGG (SEQ ID NO: 28) DV96 GGTGCATCGTAGCAGGGGGG (SEQ ID NO: 29) DV95 GGTGGTTCGATGCAGGGGGG (SEQ ID NO: 30) DV93 GGTGCATCGATGCAGGGGGG (SEQ ID NO: 12) DV92 GGTGCACCGGTGCAAAAAAA (SEQ ID NO: 31) DV81 GGTGCATCGATAGAGGGG (SEQ ID NO: 32) DV77 GGTGCATCGATGCAGGGGGG (SEQ ID NO: 12) DV76 GGTGCATCGATGCAAAAAAA (SEQ ID NO: 33) DV71 GGGGTCGACAGGG (SEQ ID NO: 34) DV49 GGTGCATAAATGCAGGGGGG (SEQ ID NO: 35) DV48 GGTGCATCAATGCAGGGGGG (SEQ ID NO: 36) DV47 GGTGCATTGATGCAGGGGGG (SEQ ID NO: 37) DV45 GGTGCATC*GATGCAGGGGGG (SEQ ID NO: 38) DV26 GGTGCATGCATGCAGGGGGG (SEQ ID NO: 39) DV20 GGTGCATGCATGCAGGGGGG (SEQ ID NO: 39) DV122 GGTGC ATTGATGCAGGGGGG (SEQ ID NO: 37) DV114 GGTGCACTGGTGCAGGGGGG (SEQ ID NO: 40) DV111 GGTGTATCGATGCAAAAGGG (SEQ ID NO: 41) DV108 GGTGCCCCGTTGCAGGGGGG (SEQ ID NO: 42) DV107 GGTGCAACGGGGCAGGGGGG (SEQ ID NO: 43) DV105 AATGCATCGATGCAAAAAAA (SEQ ID NO: 44) DV103 GGTGCACCGTGGCAGGGGGG (SEQ ID NO: 45) DV100 GGTGCATCGAAGCAGGGGGG (SEQ ID NO: 46) d79 GGTGGATCGATGCAGGGGGG (SEQ ID NO: 47) d145 GGTGCACGCGTGCAGGGGGG (SEQ ID NO: 48) d144 GGTGCATGTATGCAGGGGGG (SEQ ID NO: 49) AA20 GGGGGATCGATGGGGG (SEQ ID NO: 50) AA3M GGGGGAAGCTTCGGGG (SEQ ID NO: 51) K ODN K22 CTCGAGCGTTCTC (SEQ ID NO: 52) DV84 ACTCTCGAGCGTTCTA (SEQ ID NO: 53) K21 TCTCGAGCGTTCTC (SEQ ID NO: 54) K82 ACTCTGGAGCGTTCTC (SEQ ID NO: 55) K30 TGCAGCGTTCTC (SEQ ID NO: 56) k31 TCGAGGCTTCTC (SEQ ID NO: 57) K39 GTCGGCGTTGAC (SEQ ID NO: 58) K16 TCGACTCTCGAGCGTTCTC (SEQ ID NO: 59) K3 ATCGACTCTCGAGCGTTCTC (SEQ ID NO: 60) k23 TCGAGCGTTCTC (SEQ ID NO: 61) DV110 TCGAGGCTTCTC (SEQ ID NO: 57) K40 GTCGGCGTCGAC (SEQ ID NO: 62) DV101 CTCGAGCGTTCT (SEQ ID NO: 63) DV89 ACTCTTTCGTTCTC (SEQ ID NO: 64) K34 GTCGACGTTGAC (SEQ ID NO: 65) DV86 ACT CTCGAGCG TTCTC (SEQ ID NO: 66) K83 ACTCTCGAGGGTTCTC (SEQ ID NO: 67) K19 ACTCTCGAGCGTTCTC (SEQ ID NO: 66) DV88 ACTCTCGAGCGTTCTCAAAA (SEQ ID NO: 68) DV85 CATCTCGAGCGTTCTC (SEQ ID NO: 69) K73 GTCGTCGATGAC (SEQ ID NO: 70) DV109 TCGAGCGTTCT (SEQ ID NO: 71) D123 TCGTTCGTTCTC (SEQ ID NO: 72) D124 TCG TT TG TT CTC (SEQ ID NO: 73) K46 GTCGACGCTGAC (SEQ ID NO: 74) D139 TCGATGCTTCTC (SEQ ID NO: 75) D137 TCGCCGCTTCTC (SEQ ID NO: 76) K47 GTCGACGTCGAC (SEQ ID NO: 38) K72 GTCATCGATGCA (SEQ ID NO: 77) DV90 ACTCTTTCGATCTC (SEQ ID NO: 78) K37 GTCAGCGTCGAC (SEQ ID NO: 79) k25 TCGAGCGTTCT (SEQ ID NO: 71) D127 TGG AG CG TT CTC (SEQ ID NO: 80) D138 TGCTGCGTTCTC (SEQ ID NO: 81) D125 TTG AG CG TA CTC (SEQ ID NO: 82) D134 TGCTTCG AGCTC (SEQ ID NO: 83) D136 TGCACCGTTCTC (SEQ ID NO: 84) CONTROL K ODN DV89 ACTCTTTCGTTCTC (SEQ ID NO: 64) d112 TGCAGGCTTCTC (SEQ ID NO: 85) DV112 TTGAGTGTTCTC (SEQ ID NO: 86) DV112 TTGAGTGTTCTC (SEQ ID NO: 86) K41 GTCGGCGCTGAC (SEQ ID NO: 87) DV109 TCGAGCGTTCT (SEQ ID NO: 71) k10 ATGCACTCTGCAGGCTTCTC (SEQ ID NO: 88) K38 GTCAGCGCTGAC (SEQ ID NO: 89) k29 TCGAGCG (SEQ ID NO: 90) k26 TCGAGCGTTC (SEQ ID NO: 91) k27 TCGAGCGTT (SEQ ID NO: 92) K36 GTCAACGCTGAC (SEQ ID NO: 93) K35 GTCAACGTCGAC (SEQ ID NO: 94) K44 GTCGAGGCCGAC (SEQ ID NO: 95) k28 TCGAGCGT (SEQ ID NO: 96) AA19 GGGGGAACGTTGGGGG (SEQ ID NO: 97) D135 TGCAGCGAGCTC (SEQ ID NO: 98) D141 CCGAGGCTTCTC (SEQ ID NO: 99) D126 ACG AG GG TT CTC (SEQ ID NO: 100) K42 GTCAACGCCGAG (SEQ ID NO: 101) D140 GCGAGGCTTCTC (SEQ ID NO: 102) d121 ACTCTTGAGTGTTCTC (SEQ ID NO: 103) K45 GTCGGCGCCGAC (SEQ ID NO: 104) K43 GTCAGCGCCGAC (SEQ ID NO: 105) K24 CGAGCGTTCTC (SEQ ID NO: 106) Underlined bases are phosphodiester. *indicates methylated CG. Bold indicates self-complementary sequences. Sequence identifier is noted below the nucleic acid sequence. For each heading (IFN-g, IL-6, IgM, PROLIF (proliferation)) first column is average and second column is standard deviation.

This disclosure provides methods for stimulating angiogenesis using CpG ODN. The disclosure further provides methods for inducing the production of VEFG using CpG ODN. In addition, an model system for screening potential anti-angiogenic agents is provided. It will be apparent that the precise details of the methods described may be varied or modified without departing from the spirit of the described invention. We claim all such modifications and variations that fall within the scope and spirit of the claims below. 

1. A method of inducing neovascularization in a tissue, comprising introducing a CpG oligodeoxynucleotide into an area of the tissue wherein the formation of new blood vessels is desired, wherein the CpG oligodeoxynucleotide has a sequence as set forth as: 5′-N₁DCGYN₂-3′ (SEQ ID NO: 2)

wherein at least one nucleotide separates consecutive CpGs; D is adenine, guanine, or thymidine; Y is cytosine or thymine, N is any nucleotide and N₁+N₂ is from 0-26 bases; or 5′-N₁RDCGYTN₂-3′ (SEQ ID NO: 4)

wherein at least one nucleotide separates consecutive CpGs; RD is selected from the group consisting of GpT, GpG, GpA, ApT and ApA; YT is selected from the group consisting of TpT or CpT; N is any nucleotide and N₁+N₂ is from 0-26 bases; and wherein the CpG oligodeoxynucleotide is 8 to 30 nucleotides in length, thereby inducing neovascularization in the area of the tissue, wherein the tissue is a skin graft.
 2. A method of inducing neovascularization in a tissue, comprising introducing a CpG oligodeoxynucleotide into an area of the tissue wherein the formation of new blood vessels is desired, wherein the CpG oligodeoxynucleotide has a sequence as set forth as: 5′-N₁DCGYN₂-3′ (SEQ ID NO: 2)

wherein at least one nucleotide separates consecutive CpGs; D is adenine, guanine, or thymidine; Y is cytosine or thymidine, N is any nucleotide and N₁+N₂ is from 0-26 bases; or 5′-N₁RDCGYTN₂-3′ (SEQ ID NO:4)

wherein at least one nucleotide separates consecutive CpGs; RD is selected from the group consisting of GpT, GpG, GpA, ApT and ApA; YT is selected from the group consisting of TpT or CpT; N is any nucleotide and N₁+N₂ is from 0-26 bases; and wherein the CpG oligodeoxynucleotide is 8 to 30 nucleotides in length, thereby inducing neovascularization in the area of the tissue, wherein the tissue is the scalp.
 3. A method of inducing neovascularization in a tissue, comprising introducing a CpG oligodeoxynucleotide into an area of the tissue wherein the formation of new blood vessels is desired, wherein the CpG oligodeoxynucleotide has a sequence as set forth as: 5′-N₁DCGYN₂-3′ (SEQ ID NO: 2)

wherein at least one nucleotide separates consecutive CpGs; D is adenine, guanine, or thymidine; Y is cytosine or thymidine, N is any nucleotide and N₁+N₂ is from 0-26 bases; or 5′-N₁RDCGYTN₂-3′ (SEQ ID NO: 4)

wherein at least one nucleotide separates consecutive CpGs; RD is selected from the group consisting of GpT, GpG, GpA, ApT and ApA; YT is selected from the group consisting of TpT or CpT; N is any nucleotide and N₁+N₂ is from 0-26 bases; and wherein the CpG oligodeoxynucleotide is 8 to 30 nucleotides in length, thereby inducing neovascularization in the area of the tissue, wherein the tissue comprises a blood vessel.
 4. The method of claim 1, wherein the CpG oligodeoxynucleotide comprises the nucleic acid sequence set forth as SEQ ID NO:
 8. 5. A method of promoting angiogenesis in an area of a subject where angiogenesis is desired, comprising introducing a CpG oligodeoxynucleotide to the area, wherein the CpG oligodeoxynucleotide has a sequence as set forth as: 5′-N₁DCGYN₂-3′ (SEQ ID NO: 2)

wherein at least one nucleotide separates consecutive CpGs; D is adenine, guanine, or thymidine; Y is cytosine or thymidine, N is any nucleotide and N₁+N₂ is from 0-26 bases; or 5′-N₁RDCGYTN₂-3′ (SEQ ID NO: 4)

wherein at least one nucleotide separates consecutive CpGs; RD is selected from the group consisting of GpT, GpG, GpA, ApT and ApA; YT is selected from the group consisting of TpT or CpT; N is any nucleotide and N₁+N₂ is from 0-26 bases; and wherein the CpG oligodeoxynucleotide is 8 to 30 nucleotides in length thereby promoting angiogenesis in the subject, wherein the subject has peripheral vascular disease, and wherein the area is a vessel in which blood flow is restricted.
 6. The method of claim 1, wherein the oligodeoxynucleotide comprises the nucleic acid sequence set forth as SEQ ID NO:
 7. 7. The method of claim 2, wherein the oligodeoxynucleotide comprises the nucleic acid sequence set forth as SEQ ID NO:
 7. 8. The method of claim 3, wherein the oligodeoxynucleotide comprises the nucleic acid sequence set forth as SEQ ID NO:
 7. 9. The method of claim 1, wherein the oligodeoxynucleotide consists of the nucleic acid sequence set forth as SEQ ID NO:
 7. 10. The method of claim 2, wherein the oligodeoxynucleotide consists of the nucleic acid sequence set forth as SEQ ID NO:
 7. 11. The method of claim 3, wherein the oligodeoxynucleotide consists of the nucleic acid sequence set forth as SEQ ID NO:
 7. 12. The method of claim 2, wherein the CpG oligodeoxynucleotide comprises the nucleic acid sequence as set forth as SEQ ID NO:
 8. 13. The method of claim 3, wherein the CpG oligodeoxynucleotide comprises the nucleic acid sequence as set forth as SEQ ID NO:
 8. 14. The method of claim 5, wherein the CpG oligodeoxynucleotide comprises the nucleic acid sequence as set forth as SEQ ID NO:
 7. 15. The method of claim 5, wherein the CpG oligodeoxynucleotide consists of the nucleic acid sequence as set forth as SEQ ID NO:
 8. 16. The method of claim 1, wherein the CpG oligodeoxynucleotide comprises one of the nucleic acid sequence set forth as SEQ ID NO: 38, SEQ ID NO: 52, SEQ ID NO: 54, SEQ ID NO: 55, SEQ ID NO: 56, SEQ ID NO: 57, SEQ ID NO: 58, SEQ ID NO: 59, SEQ ID NO: 60, SEQ ID NO: 61, SEQ ID NO: 62, SEQ ID NO: 65, SEQ ID NO: 66, SEQ ID NO: 67, SEQ ID NO: 70, SEQ ID NO: 71, SEQ ID NO: 74, SEQ ID NO: 77, or SEQ ID NO:
 79. 17. The method of claim 2, wherein the CpG oligodeoxynucleotide comprises one of the nucleic acid sequence set forth as SEQ ID NO: 38, SEQ ID NO: 52, SEQ ID NO: 54, SEQ ID NO: 55, SEQ ID NO: 56, SEQ ID NO: 57, SEQ ID NO: 58, SEQ ID NO: 59, SEQ ID NO: 60, SEQ ID NO: 61, SEQ ID NO: 62, SEQ ID NO: 65, SEQ ID NO: 66, SEQ ID NO: 67, SEQ ID NO: 70, SEQ ID NO: 71, SEQ ID NO: 74, SEQ ID NO: 77, or SEQ ID NO:
 79. 18. The method of claim 3, wherein the CpG oligodeoxynucleotide comprises one of the nucleic acid sequence set forth as SEQ ID NO: 38, SEQ ID NO: 52, SEQ ID NO: 54, SEQ ID NO: 55, SEQ ID NO: 56, SEQ ID NO: 57, SEQ ID NO: 58, SEQ ID NO: 59, SEQ ID NO: 60, SEQ ID NO: 61, SEQ ID NO: 62, SEQ ID NO: 65, SEQ ID NO: 66, SEQ ID NO: 67, SEQ ID NO: 70, SEQ ID NO: 71, SEQ ID NO: 74, SEQ ID NO: 77, or SEQ ID NO:
 79. 19. The method of claim 5, wherein the CpG oligodeoxynucleotide comprises one of the nucleic acid sequence set forth as SEQ ID NO: 38, SEQ ID NO: 52, SEQ ID NO: 54, SEQ ID NO: 55, SEQ ID NO: 56, SEQ ID NO: 57, SEQ ID NO: 58, SEQ ID NO: 59, SEQ ID NO: 60, SEQ ID NO: 61, SEQ ID NO: 62, SEQ ID NO: 65, SEQ ID NO: 66, SEQ ID NO: 67, SEQ ID NO: 70, SEQ ID NO: 71, SEQ ID NO: 74, SEQ ID NO: 77, or SEQ ID NO:
 79. 